Method and apparatus for injecting perforation sealers



March 28, 1961 B. GILBERT 2, 76,928

METHOD AND APPARATUS FOR INJECTING PERFORATION SEALERS Filed June 7, 1957 TO WELL HEAD METHOD AND APPARATUS FOR INJECTING PERFORATION SEALERS Bruce Gilbert, Dallas, Tex., assignor to The Western Company of North America, a corporation of Delaware Filed June 7, 1957, Ser. No. 664,297

3 Claims. (Cl. 166-75) This invention relates to devices for feeding or injecting objects into a vessel under pressure and more particularly to an injection device for introducing sealing elements adapted to temporarily seal perforations in the casing of a well during the treatment of the well with fluid under pressure.

It is common practice to set a casing in a well bore hole, to anchor the casing in the well with cement, and then perforate those sections of the casing and surrounding cement sheath set through producing earth formations in order to provide communication between the formations and the well. Various known means of perforating the casing are employed, as, for example,

by exploding bullets and shaped explosive charges.

In completing new oil, gas or water production or injection Wells, or in renovating old wells, it is often necessary to open drainage channels or fractures in the earth formations surrounding the casing to allow production of fluid from or injection of fluid into the formations. In such cases it has become common practice to pump fluid down the casing under pressures ranging up to 10,000 p.s.i.g., or more, in order to hydraulically fracture the formations surrounding the perforated sections of the well casing. Oil, water or other fluids employed in hydraulic fracturing operations are usually loaded with sand which serves to prop open the fractures in the formation produced by'these treatments. New drainage channels are often opened up in calcareous formations by treatment with hydrochloric acid, as well as the hydraulic fracturing technique discussed hereinabove.

It is often desired to acidize or hydraulically fracture a single long zone or two or more short zones at different depths in a well. This has previously been difiicult and expensive to accomplish since dilferent pressures are normally required to inject fluid into formations at different depths in a well and consequently only that zone or section of a zone which takes fluid under the lowest injection pressure is treated. A new method designed to solve this problem is disclosed in the co-pending application of Charles M. Simmons, Serial No. 615,687, filed October 12, 1956, entitled Method for Temporarily Sealing Perforations in Well Casing." This method consists essentially in introducing well-casing sealing elements having a larger diameter than the perforations in the well-casing into the well while maintaining the treatment pressure. The well-casing sealing elements thus introduced follow the flow of treating fluid down into the well where they are forced by fluid pressure against the perforations in the well-casing through which the treating fluid flows at the lowest pressure. Continued pumping of treating fluid into the Well having the easing perforations temporarily sealed in this manner causes the internal pressure in the casing to rise sufficiently to result in a breakdown of the formation opposite pen forations which did not receive the treating fluid initially. Thus, it is possible by utilizing the method of said Simmons patent application to treat substantially completely the exposed formations in a well regardless of the fact that the pressure required to hydraulically fracture difference exposed formations or different portions of a single formation may vary over a considerable range.

The method of said Simmons patent application requires that the fluid pressure in the Well-casing be maintained in excess of the back pressure existing in the formation initially receiving fluid since a decrease in the fluid pressure in the well-casing below the back pressure might allow well-casing sealing elements already in' place in the casing perforations to drop to the bottom of the well. Thus it is necessary to provide means by which both the initial and all succeeding batches of well-casing sealing elements may be injected into the well while maintaining suflicient hydraulic pressure in the casing to prevent release of well-casing sealing elements from previously sealed perforations. Before treatment of a given well is commenced, the number of perforations in the perforated section of the well-casing to be treated is generally known making it possible to estimate the number of well-casing sealing elements required for a successful treatment.

It is a principal object of this invention to provide an injection apparatus and method whereby welhcasing sealing elements may be released into a cased well during a hydraulic treatment of the well.

It is a further object of this invention to provide means whereby the number of well-casing sealing elements released into the well-casing may be easily and accurately determined and the time of introduction easily controlled.

Further objects and advantages of this invention will be apparent from the following description thereof and the accompanying drawing in which:

Figure 1 is a diagrammatic view partly in section of a preferred embodiment of an injector apparatus of the invention for introducing well-casing sealing elements into a Well treatment line or well-casing.

Figure 2 is an enlarged section of the wire 25 showing the calibration marks 50.

Referring now to the drawing, a typical injector apparatus of the present invention comprises an injector assembly 10 connected to a Well treating means in the form of a treatment line 11 by a threaded T 12 at 28, or by any other suitable means. A high pressure pump- 13 adapted to pump treating fluid through the treatment line 11 and into the Well-casing is connected to the threaded T 12 as shown at 29.

The injector assembly 10 includes a packing gland member 14 having inner and outer ends threadedly connected to T 12 at its inner end as shown at 30. The packing gland member 14 has at its outer end a packing gland chamber '15 adapted to receive a packing gland 16 having an axial'hole (not shown). Said packing gland member 14 is also equipped with a small hole- 17 drilled along its axis between the packing gland chamber 15 and its inner end. The chamber 15 is substantially closed at 31 by a packing screw 18 which has a small hole 32 drilled along its axis. A tubular spacer 19 located within the T 12 has one end threaded at 33 into the inner end of the packing gland member 14 While the other end is closed by a cap 20 which contains a small axial hole 21. A reel 22 having a handle 23 is attached to the packing gland member 14 by a suitable bracket 24. A wire 25 is provided with an expendable solder tip 26 or other suitable means at one end thereof for retaining well-casing sealing elements 27. The well-casing sealing elements 27 which are shown as rubber balls are suitably in diameter, have hole 21 in the cap 20, the tubular spacer 19, the hole 17 in the packing gland member 14, the packing gland 16 and the packing screw 18' and then is attached to the reel 22.

When it is desired to inject well-casing sealing elements into the well, the treating fluid pump 13 is started which causes treating fluid to flow through the T 12 past the well-casing sealing elements 27 strung on wire 25, through the treatment line 11 and into the well head. The reel handle 23 is then rotated, thereby winding the wire 25 on the reel 22, which forces the sealing elements 27 against the cap and strips thesolder tip 26 from the wire 25. Continued rotation of the reel handle 23 causes the sealing elements to be stripped consecutively from the wire 25, released into the stream of treating fluid and carried into the well and down the well-casing to perform the required scaling function.

Since the number of well-cming sealing elements stripped from the wire and released into the well is proportional to the length of wire drawn over the reel 22 and through the packing screw 18, the wire may be calibrated, as shown by calibration marks 50 in Figure 2 of the drawing, to indicate the number of sealing elements released.

As will be apparent to those skilled in the art, the device of the invention may be suitably modified without departing from the scope or spirit of the invention. For example, other means may be employed to retract the wire through the sealing elements to release them. Other means may be employed to connect the various components of the apparatus to each other. Also, the means through which the wire passes from the device at the time of releasing the sealing elements may be modified.

The terms and expressions which have been employed are used as terms of description and not of limitation and there is no intention in the use of such terms and expressions to exclude the equivalents of the features shown and described or portions thereof since it is recognized that various modifications are possible Within the scope of the invention claimed.

What is claimed is:

1. Apparatus for injecting Well-casing perforation sealing elements into a Well during treatment of said well with fluid under pressure, which comprises a hollow injector assembly having one end thereof adapted to communicate with a Well treating means, reel means attached to the other end of said injector assembly, a source of fluid pressure communicating with the interior of the injector assembly through an inlet opening in said injector assembly, a' wire having a first end passing through the interior of said injector assembly and a second end attached to said reel means, well-casing sealing elements strung on said wire adjacent to said first end, said injector assembly having means to position said sealing elements with respect to said inlet opening so as to be expelled by. fluid pressure from said source of fluid pressure, and releasable restraining means attached to the first end of said wire adapted to prevent premature release of said well-casing sealing elements into said well.

2. Apparatus for injecting well-easing perforation sealing elements into a well during treatment of said well with fluid under pressure, which comprises a hollow injector assembly having one end thereof adapted to communicate with a well treating means, reel means attached to the other end of said injector assembly, a source of fluid pressure communicating with the interior of the injector assembly through an inlet opening in said injector assembly, a wire having a first end passing through the interior of said injector assembly and a second end attached to said reel means, well-casing sealing elements strung on said wire, said injector assembly having spacer means for positioning said sealing elements adjacent to said inlet opening so that said sealing elements may be expelled by fluid pressure from said source of fluid pressure, and removable restraining means attached to the first end of said Wire adapted to prevent premature release of said well-casing sealing elements intosaid Well.

3.'Apparatus for injecting well-casing perforation sealing elements into a well during the treatment of said well with fluid under pressure, which comprises a substantially tubular injector assembly having one end thereof adapted to communicate with a well treatment means and containing an axial hole therethrough, reel means attached to the other end of said injector assembly, a source of fluid pressure communicating with. said axial hole of said injector assembly, a wire having a first end passing through said axial hole of the injector assembly and a second end attached to said reel means, well-casing sealing elements strung on said wire adjacent to said first end, said injector assembly having means to posi- References Cited in the file of this patent UNITED STATES PATENTS 258,426 Jewell May 23, 1882 1,369,891 Halliburton Mar. 1, 1921 1,786,848 Johnson Dec. 30, 1930 1,791,874 Rodgers Feb. 10, 1931 1,999,559 Brendlin Apr. 30, 1955 2,745,910 Derrick et al. July 17, 1956 2,790,500 Jones Apr. 30, 1957 

